The purpose of this study is to determine whether combination antiretroviral therapy can durably reduce viral load and prevent the emergence of multidrug resistance. Three treatment regimens will be studied and at least two regimens must show the potential to reduce viral load for at least 12 weeks in order for the study to continue. This study will also assess whether viral parameters can be correlated with clinical disease progression. The antiretrovirals include AZT, ddI and nevirapine.